1. Field of the Invention
The present invention relates to a drive system, in particular for a vehicle, including an electric machine, by means of which a shaft can be driven to rotate and/or electrical energy can be obtained when the shaft rotates. The electric machine has a stator arrangement with a stator interaction region and a rotor arrangement with a rotor interaction region, the rotor interaction region being coupled or capable of being coupled to the shaft for common rotation by means of a carrier arrangement. The drive system further includes a torsional-vibration damper arrangement with a primary side and a secondary side which can rotate, counter to the action of a damper element arrangement, about an axis of rotation with respect to the primary side.
2. Description of the Related Art
A drive system of this type is known, for example, from DE 199 14 376 A1. In this drive system, the torsional-vibration damper arrangement is designed so that it is either bolted onto a drive shaft together with the carrier arrangement for the rotor interaction region, or so that one of the primary side and the secondary side is linked to the carrier arrangement for common rotation or, via this arrangement, is connected in a rotationally fixed manner to the drive shaft. The result is a structure which takes up a relatively large amount of space, but this causes difficulties in particular when drive systems of this type are integrated in a drive train of small motor vehicles.
The object of the present invention is to refine a drive system of the generic type in such a manner that the space which it takes up can be reduced.
According to the invention, this object is achieved by a drive system, in particular for a vehicle, comprising an electric machine, by means of which a shaft can be driven to rotate and/or electrical energy can be obtained when the shaft rotates. The electric machine includes a stator arrangement with a stator interaction region and a rotor arrangement with a rotor interaction region, the rotor interaction region being coupled or capable of being coupled to the shaft for common rotation by means of a carrier arrangement. The drive system further includes a torsional-vibration damper arrangement with a primary side and a secondary side which can rotate, counter to the action of a damper element arrangement, about an axis of rotation with respect to the primary side.
In this system, it is furthermore provided that the carrier arrangement forms at least a part of the primary side.
The integration of functions, i.e. the incorporation of the carrier arrangement or a section thereof into the torsional-vibration damper arrangement, makes it possible to save on the number of components, and the electric machine and torsional-vibration damper arrangement assemblies can be positioned closer together, with the advantage that the overall size or length of a system of this type can be reduced compared to systems which are known from the prior art.
To further minimize the space which has to be made available, the carrier arrangement has its region which forms at least a part of the primary side located substantially radially inside the stator arrangement and preferably axially overlaps this arrangement at least in regions.
By way of example, the carrier arrangement may form a part of the primary side which serves to support the forces of the damper element arrangement.
To ensure symmetrical transmission of forces without the risk of primary side and secondary side becoming misaligned with respect to one another, the primary side has two force-supporting regions which, at least in regions, lie at an axial distance from one another, and the carrier arrangement forms one of the force-supporting regions. This can be achieved in a manner which is simple to produce by the fact that the primary side has two cover disk regions which form the force-supporting regions, and that the carrier arrangement forms one of the cover disk regions. In this case, it is furthermore advantageously provided that the secondary side has a central disk element which engages axially between the two force-supporting regions of the primary side.
In an alternative embodiment, the carrier arrangement, in a region which extends substantially axially and radially outside the damper element arrangement, has at least one first force-supporting region for the damper element arrangement. The secondary side has a second force-supporting region, which extends substantially axially, associated with at least one first force-supporting region of the primary side. In an embodiment of this type, the at least one first force-supporting region and the associated second force-supporting region preferably lie between the end regions of two damper elements which follow one another in the circumferential direction.
In design terms, this embodiment can be made particularly simple by the carrier arrangement having a carrier element which forms the part of the primary side, that the secondary side having a driver element which has the at least one second force-supporting region, and the carrier element and the driver element together forming a rotation-angle limitation for the torsional-vibration damper arrangement. In addition to its function of being able to transmit torque in damping mode, a further integration of function is provided in this case, namely that of preventing excessive compression of the damper element arrangement as a result of the rotation-angle limitation arrangement becoming active.
To achieve further integration of functions into assemblies or components which are already present, the secondary side can be supported in the radial direction and/or in the axial direction on the carrier arrangement. In this case, the central disk element is preferably supported on the carrier arrangement, preferably via a radial bearing arrangement.
With regard to the support of the primary side with respect to the secondary side, a bearing region for axially and radially supporting the secondary side with respect to the primary side may be formed on the carrier arrangement.
To connect the two cover disk regions in a simple manner and without the insertion of additional components, one of the cover disks has a connecting section for connection, preferably by welding, to the other cover disk region. This extends axially toward the other cover disk region and preferably radially outward.
If the connecting section lies substantially radially inside the stator arrangement and axially overlaps the stator arrangement, this part of the carrier arrangement can simultaneously serve to axially bridge the stator arrangement. The torsional-vibration damper arrangement can therefore be positioned even closer to the electric machine or is arranged substantially radially inside the stator arrangement thereof or axially overlaps this arrangement.
To produce a simple connection between the two cover disk regions, the other cover disk region, by means of a connecting section thereof, preferably extends axially toward the carrier arrangement and preferably radially outward.
To obtain a stable axial support between primary side and secondary side, the secondary side can be axially supported on the carrier arrangement via the second cover disk region. In this case, the secondary side is preferably axially supported on the secondary cover disk region in or close to a transition between a section which extends substantially radially and a connecting section which extends axially and preferably radially outward toward the carrier arrangement. The axial support in this connecting region produces an axially highly stable, i.e. relatively unyielding support, since in particular even when produced from sheet-metal material, the second cover disk region is very deformation-resistant in this transition region.
For axial support, the secondary side can be supported on a second cover disk element, with an axial bearing arrangement, preferably a slide bearing arrangement, arranged between them.
In the drive system according to the invention, in particular its torsional-vibration damper arrangement, the two cover disk regions preferably form a space between them which contains the damper element arrangement. This space is at the maximum radial distance from the axis of rotation, preferably in the region of the connection between the two cover disk regions.
The force-transmitting support of the damper elements, for example damper springs, on the primary side or the secondary side often takes place with so-called spring plates or spring saddles arranged in between, allowing better distribution of pressure or load. These spring plates are then generally supported radially on the outside on a slideway which is formed in the region of one or both of the cover disk regions.
In open systems, i.e. those which do not use lubricant in this region, there is a fundamental risk of considerable and undefined friction being introduced by abraded particles which are generated in operation and accumulate between the spring plates and the slideway, and this friction may also entail considerable abrasion in the region of the spring plates. To counteract this problem, at least one particle-removal opening is provided in at least one of the cover disk regions, preferably a connecting section thereof. This particle-removal opening passes through this region or section and opens out into the space in or close to the region which is at the greatest radial distance from the axis of rotation. Providing a particle-removal opening of this nature ensures that the abraded particles which collect radially on the outside due to centrifugal force can be conveyed out of the region in which the spring plates or the spring saddles are to slide along the associated slideway.
To provide a stable support combined with a simple structure, the secondary side is axially and/or radially supported on the carrier arrangement, radially outside the connection of the second cover disk region to the carrier arrangement.
In the drive system according to the invention, the carrier arrangement preferably has a first carrier element, which forms at least a part of the torsional-vibration damper arrangement and carries the rotor interaction region, and a second carrier element, which couples the first carrier element to the shaft. Naturally, it is also possible for the first carrier element to be directly linked to the shaft.
In rotary operation, tumbling movements frequently occur, being introduced by nonuniform rotary movements in the region of the shaft, for example a crankshaft. To damp these tumbling movements in the torque-transmission path and thus also ensure that the air gap between the rotor interaction region and the stator interaction region remains approximately constant in rotary operation, the second carrier element contacts the first carrier element by means of a contact region which is convex with respect to the first carrier element and extends around the axis of rotation. The curved contour allows a minimum rolling movement of the second carrier element on the first carrier element, so that the second carrier element together with the shaft can be at least slightly inclined with respect to the axis of rotation, without this incline inevitably also being transmitted to the first carrier element.
To facilitate integrating a system according to the invention in a drive train, the secondary side is supported in the radial direction on a radially inner region of the primary side, preferably of the first carrier element, and the second carrier element is or can be coupled to the shaft radially inside the radial support of the secondary side with respect to the primary side. In this way, threaded bolts which are used for this coupling can easily be introduced in the axial direction, without any components being impeded, and can be screwed into associated threaded openings in the shaft.
In another embodiment which is preferred on account of its very simple design, the carrier arrangement has a carrier element which, in its radially outer region, carries the rotor interaction region, in its radially inner region is or can be coupled to the shaft and between its radially outer region and its radially inner region forms the part of the primary side.
To ensure that the electric machine does not overheat when operating, particularly in the region of the stator arrangement, the carrier arrangement, in the radial region of the stator arrangement, has at least one air-passage opening region and/or at least one fan blade region.
If, in the system according to the invention, contaminating particles are produced or collect therein, there is a fundamental risk of these particles passing into the air gap between the rotor interaction region and the stator interaction region. This could impair the performance of the electric machine. To counteract this, the carrier arrangement has a hollow-like particle-receiving region which is open toward the radially inner side, surrounds the axis of rotation and into which preferably at least one particle-removal opening opens. Particles can then be trapped in the particle-receiving region of the carrier arrangement, which preferably lies close to the region of the air gap or slightly radially inside it, and can be removed from this region, for example through a particle-removal opening, without there being any risk of a further movement toward the air gap.
In rotary operation, the damper elements of the damper element arrangement are forced radially outward by the centrifugal forces which are active, so that they are supported radially on the outside, for example on the primary side, with frictional forces being generated.
To reduce these frictional forces, which may lead to an undesirable effect on the damping performance, at least some of the damper elements of the damper element arrangement are radially and/or axially supported on the primary side, with a bearing arrangement in between. For this purpose, the bearing arrangement may include at least one sliding bearing element which is carried on the primary side. A coating of sliding bearing material may also be provided on the primary side. Furthermore, a very low-friction bearing can be obtained if the bearing arrangement comprises a rolling bearing arrangement which is supported with respect to the primary side and the damper element arrangement.
To be able to ensure that the system according to the invention is held together in a defined way even when it has not yet been integrated in a drive shaft or the like, it is possible to provide an axial securing arrangement which acts between the primary side and the secondary side.
As has already been mentioned, in order for particles to be removed from the region of the damper element arrangement, the damper element arrangement may be arranged in a space which is substantially surrounded by two cover disk regions, and at least one particle-removal opening, which preferably opens out into a radially outer region of the space, may be provided in at least one of the cover disk regions.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.